This invention relates to apparatus for use in handling a load which is capable of raising and lowering, or of towing, a load and also handling service cables and/or hoses connected to the load. The invention is particularly, but not exclusively, applicable to the handling of subsea equipment such as grabs.
Hitherto, providing services to underwater equipment has required the provision of a specific bundle of cable(s) and/or hose(s) dedicated to each application. For some applications, it is known to incorporate the service bundle within an armoured hoist rope. This approach has a number of deficiencies. The resulting rope is costly, gives inferior hoisting properties, and by virtue of limitations on the diameter of rope which can be handled the services which can be incorporated are limited. Further, in practice it is impossible with this arrangement to add to the length of the rope or to join different types of materials, for example wire ropes with fibre ropes.
In accordance with an aspect of the present invention, apparatus for use in handling a load comprises a load-bearing rope, a mechanism for saying out and recovering the rope, a drum for holding a service cable with a length of the service cable extending therefrom, and a wrapping device for rotating said length of service cable around the rope as the rope is payed out to wrap the service cable around the rope, and to unwrap the service cable from the rope as the rope is recovered.
In accordance with another aspect of the present invention, a method of handling a load comprises paying out a load-bearing rope and wrapping a service cable around the rope as it is payed out, and subsequently unwrapping the service cable from the rope as the rope is recovered.
The term xe2x80x9cservice cablexe2x80x9d is used herein to denote a flexible elongate member used for conveying power or data, such as an electrical cable, a fibre optic cable, or a pneumatic or hydraulic hose.
Preferably, the service cable is wrapped helically around the rope.
Typically, the load-bearing rope will be a hoist rope used for raising and lowering a load. Alternatively, the load-bearing rope may be a towing rope used for paying out, towing and recovering a load such as a marine sensor array.
The apparatus may include a plurality of service cables each extending from a respective drum.
Preferably, the mechanism for paying out and recovering the rope comprises a rope winch, from which the rope passes over a rope sheave and thereafter extends to the load along a substantially straight axis.
The wrapping device may comprise the or each service cable drum being arranged for rotation about a drum axis which coincides with said axis, the drum typically having a central aperture through which the load-bearing rose passes, said length of service cable preferably passing over a service cable sheave which is mounted for movement in a circular path around said axis.
Alternatively, the or each service cable drum may be rotatable on a structural member which is arranged for movement in a circular path about said axis.
The hoist rope winch, the or each service cable drum, and the wrapping device may conveniently each have a respective driving motor; they could however be driven by a single source through appropriate mechanical linkages.